The present invention relates to a data bus interface for a control unit, in particular for a motor vehicle control unit. The present invention also relates to a control unit, in particular a motor vehicle control unit, having a data bus interface for accessing a data bus for communicating with at least one other control unit via the data bus.
In this case, the interface is an interface between one or more microprocessors and a data bus. The interface conditions signals of a microprocessor which are to be transmitted to another microprocessor via a data bus according to a selected transmission protocol (e.g. CAN (Controller Area Network), TTCAN (Time-Triggered CAN), MOST (Media-Oriented Systems Transport), FlexRay, etc.) before they are injected into the data bus. The interface may be part of a control unit, in particular part of a motor vehicle control unit. In this case, control programs may be run on the microcontrollers for performing a normal control and/or regulation function, and they may be used to control and coordinate communication via the data buses. However, it is also possible to use the microcontrollers of the interface only to control and coordinate communication via the data buses and to obtain the data to be transmitted from other microcontrollers and to merely forward the data received. At least one control unit is connectable to a data bus via an interface. The control units connected to the same data bus may then exchange information with each other via the data bus.
Providing not only one, but also two or even more arithmetic units, in particular microprocessors in the form of microcontrollers in a CAN interface, is conventional. Generally, however, only those microprocessors which have only one CAN controller are combined in a CAN interface. However, microcontrollers having more than one, for example two, CAN controllers are also conventional. A CAN interface having multiple microcontrollers is therefore conventional. In addition, a CAN interface which has only one microcontroller, which, however, includes a plurality of CAN controllers, is conventional.
According to the related art, in a CAN interface having multiple microcontrollers internal communication between the individual controllers takes place via a dual-port RAM (random-access memory). However, these are very expensive and power-intensive. The automotive industry, in particular, contends with enormous cost pressure and does not have unlimited quantities of power available. The use of dual port RAMs for communicating between microprocessors in a multiprocessor system is therefore not a particularly suitable solution for motor vehicles.